Production of bulked yarn



United States Patent F US. Cl. 57157 2 Claims ABSTRACT OF THE DISCLOSURE Production of crimped thermoplastic polyamide yarns by heating and false twisting polyamide multifilament yarns containing 0.05-1% by weight of a crystal nucleating agent.

This invention relates to a process for the production of bulked yarns of thermoplastic high polymers by heating and twisting, thermoplastic high polymers which contain crystal nucleating agents being used.

It is known that bulked yarn of thermoplastic high polymers, for example polyamides, may be produced by heating a yarn consisting of one or more filaments, twisting it by means of a false-twist mechanism and setting the twist while the yarn is still hot.

In the crimping equipment conventionally used, the yarn coming from the supply package passes over a tfeed roller, then through a treatment zone in which it is subjected to a wet treatment and/or a heat treatment, then through the twist head of the false-twist machine and finally to a delivery roller. The yarn is in a highly twisted condition shortly after leaving the feed roller and is untwisted again immediately after the twist head.

The crimping effect in the case of yarn which has been twisted by prior art methods is still in need of improvement.

We have now found that crimped thermoplastic high polymer yarn, particularly polyamide yarn, may be prodluced particularly advantageously be heating and twisting yarn consisting of a plurality of individual filaments when thermoplastic high polymer yarn is used which contains crystal nucleating agents (i.e. substances which form crystal nuclei).

Yarn made in this way has greater extensibility and higher hulk than yarn which has been crimped [by prior art methods. Woven or knitted fabrics which have bee-n made from yarn cn'mped in accordance with this invention have a particularly warm handle.

The process according to this invention may be carried out by conventional methods on a false-twist device. The false-twist device may consist for example substantially of a supply package, heating zone, a false-twist head and a take-up package.

The following are particularly suitable as crystal nucleating agents which may advantageously be used in amounts of 0.05 to 1% by weight: plastics whose melting point is higher than that of the thermoplastic from which the yarn is made, nylon 22 (polyethylenediamine oxalate), pigments in finely divided condition or dyes. Moreover crystal-forming substances conventionally used in the pro- :duction of polyamides having fine crystalline structure by extrusion may also be used.

Suitable synthetic high molecular weight polymers of which the yarn may consist are polyamides, particularly nylon 6 polycaprolactam. Saturated polyesters or polypropylene are also suitable.

Bulked yarn prepared according to this invention is 3,434,278 Patented Mar. 25, 1969 particularly suitable for the production of extensible knitted and woven goods.

The invention is illustrated by the following examples in which parts are parts by weight.

EXAMPLE 1 A polyamide yarn having a relative viscosity of 2.6 and a total denier of 70 has a false twist inserted at the rate of 4120 turns per meter at 185 C. and is then doubled with a similarly treated yarn twisted in the opposite direction to 140 total denier at turns per meter. The product has a crimp rigidity of 65.1%.

A yarn treated in the same way whose raw material was treated with 0.1% of a crystal nucleating agent (nylon 22) prior to spinning, however, has a crimp rigidity of 70.7%.

EXAMPLE 2 A 70 denier polyamide yarn having a relative viscosity of 2.6 is passed at 180 C. through a false-twist machine to insert a twist of 3800 turns per meter and is then doubled at 80 turns with a similarly treated yarn which has been twisted in the opposite direction. The product has a crimp rigidity of 67.6%. Practically the same crimp rigidity (68.9%) is obtained when 0.1% of a crystal nucleating agent (nylon 22) is added to the textile raw material, under otherwise identical conditions, but the effect is obtained at only 3300 turns per meter. This represents an increase in rate of production in the ratio of about 1.2: 1.

EXAMPLE 3 A 60 denier polyester yarn consisting of 12 filaments has a false-twist inserted at the rate of 3160 turns per meter at 225 C. and is then doubled with a similarly treated yarn twisted in the opposite direction to total denier at 80 turns per meter.

Under a load of 0.025 g./ den. the yarn thus obtained has a residual extensibility to the fully extended condition of 3.1%. A similarly treated yarn made from a raw material to which 0.3% of magnesium oxide has been added as crystal nucleating agent prior to spinning is capable of extension by 3.6% beyond its extension at a load of 0.025 g./ den.

We claim:

1. A process 'for production of crimped, thermoplastic rpolycaprolactam yarn by heating and then twisting polyamide multifilament yarn wherein the filaments are polycaprolactam filaments containing, as a crystal nucleating agent, 0.051% of polyethylenediaimine oxalate.

2. A process as claimed in claim 1 wherein said yarn is false twisted.

References Cited UNITED STATES PATENTS 3,069,837 12/1962 Olson 57157 3,080,345 3/ 1963 Brooks et a1 260-78 3,182,100 5/ 1965 Bedell 260857 3,216,965 11/1965 Cipriani 260857 XR 3,228,996 1/1966 llling 260857 3,247,16 8 4/1966 Stoelf 260857 XR 3,343,364- 9/ 1967 McIntosh 28-72 XR FOREIGN PATENTS 646,748 8/ 1962 Canada. 703,754 2/1965 Canada.

STANLEY N. GILREATH, Primary Examiner. W. H. SCHROEDER, Assistant Examiner.

US. Cl. X.R. 28-72; 260857 

